Fire-resisting fiber board or like article and method of making the same



ISIDOI'L KITSEE,

Patented May 23, 1933 warren srarns PATENT QFFIfiE DECEASED, LATE OF PHILADELPHIA, PENNSYLVANIA, BY W.

BROWN, EXECUTOR, OF PHILADELPHIA, PENNSYLVANIA, ASSIGNOR T0 MINERAL- ITE CGE-PGRATION, QT PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF PENN- SYLVANIA FIRE-RESISTING FIBER BOARD 03 LIKE ARTICLE AND METHOD OF MAKING- TI-IE SAME No Drawing.

The present invention relates to fiber boards. blocks, or the like and to methods of making the same, and particularly to articles of this type and methods of'making such articles in which the principal ingredient thereof is mineral wool.

It is well-known that mineral wool is an excellent insulating snbstancaand various attempts have been made to fabricate insulating blocks, boards, or like objects from it. Where mineral wool alone is employed in the manufacture of such boards, however, the results have so far not been entirely satisfactory in one respect, that is, that the resulting board has been low in tensile strength unless a heavy and dense binder was employed, the strength of the board eing largely due to the use of a particular binder. Binders of such character as to render the board mechanically strong,-however, have atthe same time rendered the board less capable of effective insulation, the binder filling the interstices of the board and reducing the number of spaces in which air is entrapped. For maximum insulating properties, the board should contain as many air spaces as possible.

In accordance with the present invention, a board of excellent heat insulating properties is produced which at the same time has the necessary mechanical strength so that it is well adapted for use as a building unit. Mechanical strength is imparted to the board not by the use of a heavy binder but by the use of fiber of greater tensile strength than that of mineral wool fiber, such fiber being intermingled with the mineral wool fibers to a degree sufficient to strengthen the board to the desired amount. The invention contemplates especially the use of wood fibers, which fibers are treated in such manner that the resulting board loses little, if any, of its fireresisting properties. The wood fibers have a very considerable tensile strength as compared with the mineral wool fibers so that the product stands up in shipment and may be shaped by suitable tools when put into use, without disintegration thereof. In the following paragraphs, a

Application filed January 2'7, 1932. Serial No. 589,318.

preferred method of producing boards of this type will be set forth.

The wood fiber used as an ingredient in the manufacture of the boardmay comprise paper pulp, shreds of wood, ground chips,

or in fact any wood which has been reduced to fibrous form. This wood fiber is treated in an alkaline bath, for instance, a bath consisting in a ten per cent solution of caustic soda in water. the bath until completely saturated, and preferably the bath temperature is maintained at from 120 to 150 F. Any temperature may be used, however, which is less than the boiling point of the caustic.

introduced into a tank or beater containing a carrier liquid such as water, and into this tank is also introduced a quantity of mineral wool, the mineral wool being added until the mineral wool fibers comprise from fifty per cent to ninety per cent of the total fiber content. The bath is then agitated so that the wood fiber and the mineral wool fiber are brought into suspension. During this time, the bath is preferably maintained alkaline, generally comprising a ten per cent 35 solution of caustic soda. This is desirable so that thewood fiber will lose none of its caustic by washing.

After the wood and mineral wool fibers have been brought into a satisfactory state 99 of suspension, the carrier liquid with its suspended fibers is removed from the beater or tank and passed on to a forming machine of some suitable and well-known type where the fiber is separated from the liquid. Thus,

the pulp stock from the beater may be passed on to the forming wire of a fiber board making machine, the liquid passing rapidly through the openings in the wire and the fibers being collected in a layer upon 100 The fiber is maintained in 60 so that a maximum saturation is re- 70 similar object may be subjected to great pressure if desired to not only compact the fibers but to express some of the contained 11 uid and after this )ressure the artlcle l is dried. If desired, a. binding substance such starch or silicate of soda may be added to the liquid in the beater so that, upon drying, the completedobjectis rigid and possesses a very substantial amount of mechanical strength.

' .lVood fibers are preferably employed by reason of their availability, cheapness, and mechanical strength. By impregnating the wood fibers with caustic, they are rendered practically fireproof or atleast in such condition as to strongly resist combustion. Prolonged heating may cause them to smoulder but not to burst into flames. The resulting board, block, or other object is, therefore, practically fireproof. It is also light in weight, has higl insulating properties, is mechanically strong, andin general is 'well adapted for use in the building industry, for the lining of refrigerators, and any other purposes where a heat insulating member is desired.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is 1. The method of making a fire-resisting fiber board or like article which comprises saturating wood fiber with caustic, introducing such fibers and mineral wool fibers into a body of a carrier liquid in a vessel and bringing said fibers into suspension by agitating said carrier liquid, the mineral wool fiber comprising from fifty per cent to ninety per cent of the total fiber content of the liquid, and separating the carrier liquid from the fibers by passing the same through a foraminous member. '1

2. The method of making a fire-resisting fiber board or like article which comprises saturating the wood fiber with caustic by maintaining said fiber for a substantial period of time in a heated bath comprising a ten per cent solution of caustic soda in water, introducing such fibers and mineral wool fibers into a body of the. carrier liquid in a Vessel and bringing said fibers into suspension byagitating said carrier liquid, the mineral wool fibers comprising from fifty per cent to ninety per cent of the total fiber content of the liquid, and separating the carrier liquid from the fibers by passingthe same through a foraminous member.

3. The method of making a fire-resisting fiber board or like article which comprises saturating wood fiber with caustic, introducing such fibers and mineral wool fibers into a body of a carrier liquid in a vessel and bringin said fibers into suspension by agitating said carrier liquid, the mineral wool fiber comprising from fifty-per cent to-ninesaturating wood fiber with caustic, introducing such fibers and mineral wool fibers into a hodyof a carrier llquid 111 a vessel and bringingsaid fibers intosuspension by agitating said carrier llquid, the mineral wool fiber comprising from fifty per cent to ninety per cent of the total'fiber content of the liquid, separating the carrier liquid from the fibers by passing the same through a foraminous member, and subjecting the sep arated fibers to pressure.

5. A fire-resisting fiber board or like article comprising intermingled fibers of mineral wool and wood, the wood fiber being saturated with an alkaline substance.

In testlmony whereof I hereunto afiix my signature.

R. V. BRO'WN, Executor of the Estate of lsz'clor Kitsce,

Deceased. 

